diff --git a/error.py b/error.py
index 783ab7d..2148248 100644
--- a/error.py
+++ b/error.py
@@ -25,6 +25,7 @@
   """Unspecified error from the user's text editor.
   """
   def __init__(self, reason):
+    super(EditorError, self).__init__()
     self.reason = reason
 
   def __str__(self):
@@ -34,6 +35,7 @@
   """Unspecified internal error from git.
   """
   def __init__(self, command):
+    super(GitError, self).__init__()
     self.command = command
 
   def __str__(self):
@@ -43,6 +45,7 @@
   """A bundle upload to Gerrit did not succeed.
   """
   def __init__(self, reason):
+    super(UploadError, self).__init__()
     self.reason = reason
 
   def __str__(self):
@@ -52,6 +55,7 @@
   """Cannot download a repository.
   """
   def __init__(self, reason):
+    super(DownloadError, self).__init__()
     self.reason = reason
 
   def __str__(self):
@@ -61,6 +65,7 @@
   """A specified project does not exist in the work tree.
   """
   def __init__(self, name=None):
+    super(NoSuchProjectError, self).__init__()
     self.name = name
 
   def __str__(self):
@@ -73,6 +78,7 @@
   """A specified project is not suitable for the specified groups
   """
   def __init__(self, name=None):
+    super(InvalidProjectGroupsError, self).__init__()
     self.name = name
 
   def __str__(self):
@@ -86,6 +92,7 @@
      use exec to re-execute repo with the new code and manifest.
   """
   def __init__(self, extra_args=None):
+    super(RepoChangedException, self).__init__()
     self.extra_args = extra_args or []
 
 class HookError(Exception):
@@ -93,4 +100,3 @@
 
   The common case is that the file wasn't present when we tried to run it.
   """
-  pass